The present invention relates to a combination of a towing vehicle, such as a tractor, and an agricultural harvesting machine, such as a baler or a self-loading forage wagon, drawn thereby.
Agricultural harvesting machines such as balers or self-loading forage wagons, which are drawn across the field by a towing vehicle, are often used in the harvesting of green crop. The aforementioned harvesting machines are typically supplied with drive power by the towing vehicle in order to drive available working assemblies of the harvesting machine (e.g., pick-up device, cutting device, feed rake, baling ram), which are used to convey and/or process the picked-up crop. The towing vehicle, which is usually a tractor, is equipped with a P.T.O. output shaft on the rear side for this purpose, wherein the P.T.O. output shaft is drivingly connected to a drive shaft assigned to the harvesting machine. The P.T.O. output shaft of the tractor is driven by the drive engine of the tractor. Therefore, the drive engine of the tractor, the P.T.O. output shaft and the drive shaft of the harvesting machine are essential elements of a drive train for driving the working assemblies of the harvesting machine.
When a block baling press drawn by a tractor is used for harvesting, it is difficult for the driver of the towing tractor to have a reliable overview of a large number of dynamically changing operating parameters, which play a role in the success of the harvesting process during the travel across the field. Factors such as the type, quantity, volume, moisture content or any other property of the picked-up crop, for example, greatly influence the harvesting process. Furthermore, machine-related factors affect the harvesting process, such as the power reserve and rotational speed of the drive engine of the tractor, the ground speed of the tractor (and the baler drawn thereby), the speed and load of individual working assemblies (e.g., pick-up device, cutting rotor, feed rake, baling ram) of the press, etc.
The factors have a complex interaction with one another, in part, and usually change dynamically during the harvesting operation. A particular challenge for a driver is therefore that of, inter alia, selecting a suitable ground speed during the harvesting operation. The selected ground speed must not be too high, in order to ensure that the combination of tractor and baler can be operated during the harvesting operation with a sufficient power reserve of the drive engine in order to prevent the drive train from coming to a standstill and/or to prevent damage to the machine or injury to persons in the event that harvesting and/or operating conditions change abruptly.
Due to the dimensions and shape of a field that is being worked, a tractor-baler combination is not always located in a harvesting situation of the type described above during field work, i.e., in an operating state in which the baler picks up crop in order to process this crop. For example, after travelling down a “run” (i.e., a driving path that is largely straight or slightly curved, in which an uninterrupted harvesting process can take place), the end of the field (also referred to as the headland) is reached, and therefore the tractor-baler combination must make a turning maneuver in order to continue harvesting along a subsequent run, which is usually laterally offset relative thereto. Harvesting is typically not carried out during travel in the headland.
In order to carry out the turning maneuver at the end of the field, the driver of the tractor must keep his or her eye on a plurality of parameters on the tractor and the baler in order to carry out various tasks simultaneously. For example, upon reaching the end of the field, an experienced driver simultaneously adjusts the ground speed, raises the pick-up device and steers the tractor around a curve. The driver also may lower the speed of the P.T.O. output shaft in order to save fuel. The driver carries out these tasks in reverse order upon leaving the end of the field, in order to start the harvesting process again.
From the field of tractors it is known, per se, with regard to tools that are mounted on the tractor, e.g., a plow, to reproduce, inter alia, the reciprocating motions thereof during a turning maneuver in accordance with previously stored working processes. Reference is made to EP 0 903 656 B1 in this regard. The number of operating procedures that the driver must be carry out repeatedly during a turning maneuver is therefore reduced, thereby helping to relieve the driver, since all that the driver needs to do is initiate the execution of the stored working processes.
The disadvantage of implementing this technology on a tractor-baler combination is that the time sequence in which the stored working processes are carried out is fixed. Time-dependent control is not always suitable when harvesting green crop, since, in this case, the spacing between adjacent runs (depending on the position of the particular swath) and, therefore, the driving routes in the headland, can vary to a great extent and therefore require different lengths of time to traverse.